Automatic transmission of synchronizing pulses



7 Jan. 23, 1934. M. H. WOODWARD AUTOMATIC TRANSMISSION OF SYNCHRONIZING PULSES Filed Jan. 23, 1932 Patented Jan. 23, 1934 AUTOMATIC TRANSMISSION SYNCHRONIZIN G PULSE S Marion H. Woodward, Brooklyn, N. Y., minor to International Communications Laboratories, Inc., Newark, N. J., a corporation of New York Application January 23, 1932. Serial No. 588,373

6 Claims.

This invention relates to transmitters for automatic telegraph systems, and more particularly to transmitters for systems using a previously perforated tape. These tapes normally pass over I transmitting pins or peckers which, in turn, complete electrical circuits for the transmission of impulses to a line or cable.

One of the principal difiiculties experienced in the past, in operating automatic transmitters,

I is that the apparatus at the communicating stations could not be kept in synchronous operation upon the changing of tapes, the breaking of the tape, the termination of the tape, etc.

One of the purposes of my invention is to I! maintain synchronism between the instruments at the various stations whenever the tape has run out or has broken. This is accomplished by providing means for automatically transmitting synchronizing signals over the line at intervals 50 even though no tape is in the transmitter.

Transmitting apparatus of the general type used herein is more specifically disclosed in the patent to W. C. Peterman, No. 1,542,779, issued June 16, 1925, to which reference may be made for a more complete and detailed description of the apparatus.

The nature and advantages as well as other objects of my invention will be clearly set forth in the following description, when read in conjunction with the drawing which shows one embodiment of my invention. This disclosure, however, is illustrative only, and changes may be made in the arrangement of the various parts and their mode of association without going be- 6 yond the principles of the invention or exceeding the scope of the terms in which the appended claims are expressed.

Referring to the drawing, the figure is an illustrative diagram of the electrical circuits as connected to the usual tape transmitter. The type of automatic transmitter used in this disclosure is well known to those versed in the art. Furthermore, since this transmitter mechanism 5 forms no part of this invention, it is deemed unnecessary to describe the particular means involved or to show it in the drawing in detail.

The shaft 10, in addition to carrying the cam 45, also carries a starwheel for advancing D the tape through the transmitter. This shaft is normally driven by a constant-speed motor 51 preferably of the phonic wheel type through gear 52. The eccentric or cam 18 is formed so' as to have a very gradual eccentric curve, there- 5 by avoiding sudden Jolting of the associated contacts. It also is driven by the above-mentioned phonic wheel through gear 54.

Pecker pins 16, 17 enter the successive perforations of a transmitting tape 53, The peckers, in turn, are pivoted to bell crank levers 14, 15, which in turn are reciprocated by cam 18, carried by shaft 20, and driven by the phonic wheel. Bell-crank lever 14, carrying pecker-pin 16 on one arm, has the dash contact 23 secured to one of its arms; similarly, dot contact 24 is secured to an arm of bell-crank lever 15, to which pecker-pin17 is pivoted. v

Lever 25 is a means for insuring the closing of the circuit at the proper time and has curbing contact 26 mounted at one end. This lever is also actuated by cam 18. The curbing contacts 26, 27 are included in both the dot and dash circuits, so that neither circuit is completed until the curbing contacts are closed. Bell crank levers 14, 15 and 25 are mounted on shaft 21.

In the drawing, numeral 1 is a marginal relay, 2 is a dot transmitting relay, and 3 is a dash transmitting relay. These are normally biased to spacing position by biasing windings 6, 8 and 10, respectively.

When tape is ,in the transmitter, signals are sent out in the normal manner and the transmitting and receiving instruments are maintained in synchronism by the transmitted current impulses, in the'manner well understood by those versed in the art. Thus, for transmitting dots the dot transmitting relay 2 is operated from positive battery through the curb contacts 26, 27, the dot contacts 24, the operative winding 7 of the dot transmitting relay 2, and the operative winding 4 of the marginal relay 1 to negative battery. The dash transmitting relay is operated in the same manner through the curb contacts 26, 27, the dash contacts 23, the operative winding of the dash transmitting relay 9, and the winding 5 of the marginal relay 1 to negative battery.

Whenever spaces are to be transmitted, neither the dot nor the vdash contacts are closed and the spacing bias of the respective relays causes all three to return to or to remain on their spacing contacts, and thus no signal is transmitted to the line.

For example, a spacing current of 15 mils and a marking current of 35 mils may be used in each of relays 2 and 3, while a spacing current of 50 mils may be used in marginal relay 1. Since marking coils 4 and 5 of relay 1 are each in series with 7 and 9, respectively, of relays 2 and 3, an effective current of 70 mils passing through over the cable.

the, combined coils 4 and 5 will cause relay 1 to mark. But this cannot occur while the tape is passing through the transmitter. My invention provides means, when the tape runs out, for automatically sending a series of impulses over the line at regular intervals. This automatically maintains the associated apparatus in synchronous operation until another perforated tape is inserted into the transmitter.

Marginal relay 1 operates when both pecker rods are in the elevated position. This occurs only when the tape has run out. Under this condition all three relays are in marking position. This causes a circuit to be conditioned for operation upon the subsequent making of the-curbing contact from curbing lever 25, line 11, marking contact of relay 1, line 12, and either one of contacts 28 and 29, to short coil 7 of relay 2 or coil 9 of relay 3, respectively, upon the passage of cam follower 31 over undulation 45A or depression 4:53, respectively, of cam 45. Thus, with the particular cam 45 illustrated in the position shown in the drawing, no signal is transmitted. If the tape is then run out, all the relays will mark upon the making of the curbing contacts and, as shown, the cam 45 will cause neither dot nor dash relays to be shorted and, therefore, will cause their respective tongues to be thrown to their associated. marking positions. Now, conditions remaining unchanged, namely, with the tape run out and all relays marking, then, as curbing contacts 26, 27 close and undulation 45A of cam 45 passes over cam follower 31, coil '7 of the dot transmitting relay 2 is shorted through the following circuit: shaft 21, line 11, marking contact oif relay 1, line 12, contact 28, line 13, and operative winding 4 of marginal relay l. The result of this short circuit is to cause the tongue of relay 2 to go to spacing position, thereby putting positive battery to ground and negative battery to the cable, which in conven-- tional practice results in transmitting a dash Similarly, conditions still remaining the same, then, as curbing contacts 26,

27 remain closed and cam follower 31 passes overdepression 453, coil 9 of the dash transmitting relay 3 is shorted through the following circuit: shaft 21, line 11, marking contact of relay 1, line 12, contact 29, line 30, and operative winding 4 of marginal relay 1. The result of this short circuit is to cause the tongue of relay 3 to go to spacing position, thereby putting negative battery to ground and positive battery to the cable, which in conventional practice results in transmitting a dot over the cable. In the diagram, the cam follower Sl is arranged to short-circuit coils '7 and 9 alternately for four-twentieths of a revolution of the cam 45, and is blank, shorting neither coil, for sixteemtwentieths of a revolution of the cam 45. Thus, the synchronizing signal transmitted will be the letter C, dash, dot, dash, dot, and 16 spaces repeated periodically. Obviously,

the cam 45 may be cut to transmit any desirable signal combinations. The interval of 16 spaces may be provided to allow the operators at the various stations in the system to examine their apparatuses during this idle time.

What is claimed is:

1. In. a telegraph system, the combination of a sending station, a line, an automatic tape transmitter at the sending station, a pair of biased transmitting relays controlled by said transmitter, abiased marginal relay having two operating-coils, each one being in series connection with one of said transmitting relays,

saidmarginal relay being operative upon the excitation of both its operating coils to condition a circuit for periodically transmitting a predetermined combination of impulses over the line for maintaining synchronism in said system.

2. In a transmitting system, the combination of a sending station, a line, an automatic tape transmitter at the sending station, a dot transmitting relay and a dash transmitting relay, operating circuits for both relays controlled by the tape transmitter. a third relay operating upon simultaneous closure of the operating circuits of both transmitting relays, and a circuit conditioned by operation of the third relay for periodically transmitting a predetermined combination of impulses over the line for maintaining synchronism in said system.

3. In a transmitting system, the combination according to claim 2, characterized in this, that a cam operated-by said transmitter determines the said combination of impulses.

4. In a transmitting system, the combination according to claim 2, wherein a cam operated by said transmitter determines the said combination of impulses, characterized by the provision of contacts operated by said cam to remove one of the transmitting relays from operative rela-' tion with the operating circuit therefor.

5. In a transmitting system, the combination according to claim 2, wherein a cam operated by said transmitter determines the said combination of impulses, characterized by the provision of contacts closed by said cam to shortcircuit the operating winding of one of the transmitting relays.

6. In a transmitting system, the combination of a sending station, a line, an automatic tape transmitter at the sending station, dot and dash contacts for the transmitter, a dot transmitting relay and adash transmitting relay controlled by the respective contacts, a third relay operating upon simultaneous closure of both the dot and the dash contacts when the tape runs out, a cam operated by said transmitter, and circuits controlled by said cam during its operation while said third relay is in its operated position for causing said transmitting relaysto periodically transmit a combination of impulses determined by said cam over the line for maintaining synchronism in said system.

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